Magnetic concentrate washing means for submerged belt magnetic separators



Aug. 10, 1948. R. E. CROCKETT 2,446,813

MAGNETIC CONCENTRATE WASHING MEANS FOR SUBMERGED BELT MAGNETICSEPARATORS Filed June 24, 1944 27; ,m'flffmi iiiiiilllllliiiiifi -5uvwsuroa M M A RA/EYS.

'middlings from the belt.

Patented Aug. 10, 1948 MAGNETIC CONCENTBATE WASHING MEANS FOR SUBMERGEDBELT NETIC SEPARATORS MAG- Robert E. Crockett, Upper Montclair, N. J.,assignor to Dingo Magnetic Separator 00., Milwaukee, '18., a corporationof Wisconsin Application June 24, 1944, Serial No. 541,952

The present invention relates generally to improvements in the art ofseparating mixed materials having difierent characteristics, and relatesmore particularly to various improvements in the construction andoperation of machines for effecting automatic separation of magneticmaterial from non-magnetic substances.

The primary object ofmy invention is to provide an improved magneticseparator which is simple in construction and efficient in operation.

When separating granules of magnetic ore from a granular mixture oftailings, middlings and ore particles, it is a relatively simple matterto remove the tailings from the middlings and concentrates, butconsiderable difliculty may be encountered in effecting final separationof the concentrates from the middlings. Such magnetic separation hasheretofore been accomplished with machines of the type shown anddescribed in my copending application Serial No. 365,183, filed November11, 1940, now Patent No. 2,410,601, dated November 5, 1946, wherein themixture of magnetic and nonmagnetic particles is conveyed by a. movingbelt through one or more liquid basins and from thence through a finalwashing and separating space extending at an oblique angle upwardly awayfrom the basins and which is subjected to relatively strong magneticinfluence. In this prior machine, the mixture of middlings andconcentrates which is carried by the belt into the final separatingspace, is subjected to the washing action of a multiplicity of discreteand forceful jets of liquid which are projected across the space andagainst the layer of material being held against the travelling belt bymagnetic force, and these jets have a tendency to gouge or plow into thelayer thereby dislodging concentrates as well as In order to reclaimthese concentrates, the fin al washing space or zone is limited inheight so that all portions thereof are subjected to the strong magneticinfluence, and the dislodged concentrates are thus quickly returned tothe conveying surface of the belt. Most of the middlings which areremoved from the belt by the forceful jets of washing liquid, 4

however, remain within the strong magnetic field and a substantialportion of these middlings are also immediately recaptured by the beltwith the returning concentrates, thus resulting in the production offinal concentrates containing a considerable quantity of middlings.

It is therefore a more specific object of my present invention toprovide improvements in magnetic separating machines of the abovedescribed general type, wherein more efiective automatic 14 Claims. (Cl.209-225) separation of the magnetic and non-magnetic ingredients of agranular mixture, may be accomplished,- and purer concentrates are thusobtained.

Another specific object of this invention is to provide a simplified andmore reliable magnetic ore separating system, wherein the product ismost eiiectively subjected to gentle final washing and cleansing withoutintroducing excessive loss of magnetic particles.

A further specific object of the invention is to provide improvedinstrumentalities for effecting delivery of washing liquid to the finalseparating and cleansing space or zone of a magnetic separator, and forinsuring prompt removal of the non-magnetic ingredients from the washingspace.

Still another specific object of my invention is to provide variousimprovements in the construction and operation of endless belt magneticseparators whereby the structures are simplified and the operatingefficiency is enhanced to a maximum.

These and other objects and advantages will be apparent from thefollowing detailed description.

A clear conception of a typical embodiment of my present improvement andof the normal functioning thereof, may be had by referring to thedrawing accompanying and forming a. part of this specification whereinlike reference characters are employed to designate similar parts in thevarious views.

Fig. 1 is a. somewhat diagrammatic and part sectional side elevation ofa typical magnetic separator embodying the invention;

Fig. 2 is an enlarged top view of the pan or trough which cooperateswith the conveyor belt to provide the final separating and washingspace, with the water jet deflector omitted;

Fig. 3 is a similarly enlarged fragmentary central longitudinal verticalsection through the elements forming the final separating and washingspace;

Fig. 4 is a likewise enlarged vertical transverse section through thetrough of Fig. 2, the water ticular type, it is not my desire to therebyunnecessarily restrict the scope of the claims or the utility of theimproved features.

, 4 indicated locations. This flat liquid jet which issues from theelongated straight slot 20 should having lower pole-faces disposed inclose proximity to and above the lower movable loosely sagging stretchIn of the belt 6; a feed chute or tray II for feeding a granular mixtureof magnetic and non-magnetic material to the lower face of the beltstretch I0 near the lower pulley I; a

tailings hopper l2 forming a liquid basin adjoining the feed tray H andhaving arelatively low v liquid-level l3 therein; a middlings hopper Hforming another liquid basin adjoining the tailings hopper l2 and havinga higher liquid level therein; a magnetic material or concentratesdischarge device it for delivering the final con-- centrates from themachine; a fixed plate or trough l1 interposed between the hopper l4 andthe device l6 and coasting with the belt stretch l 0 to provide a finalseparating and washing space 18 inclined upwardly away from the liquidlevel IS; a pipe or conduit I9 spanning the trough l1 and having anelongated slot 20 and a similarly elongated deflector 2i for directing afiat jet 'of liquid downwardly along the washing space l8; and meansincluding pipes 22 and a valve 23 for admitting liquid preferably undersubstantiaily equal pressure to the opposite endsof the conduit l9.

Rotation is preferably imparted to the upper belt suspension pulley 8 soas to constantly advance the lower belt stretch ill in the directionindicated by the arrows, and the pulley 8 may also be provided withsuitable belt'tension adjusting mechanism 24 for causing the conveyorstretch 'III to properly coact with the magnets 9. The magnets 9 are ofsomewhat less width than the belt 6, and are operable to create arelatively strong magnetic field along the mid-portion of the bottomsurface of the lower belt stretch ID,

in order to cause the magnetic material to adhere to this belt surfaceand to be thus transported through the hoppers l2, H and through thefinal separating space l8. The concentrates discharge device is locatedat the upper terminus of the magnetic field produced by the magnets, andthe stationary trough ,1! whichprovides the final separating and washingspace I8 is formed and located-so asto cause the entire mid-portion ofthe spaceto be constantly subjected to the strong magnetic field, whilethe oppo thereof indicated by the dot-and-dash lines' in Fig. 2, arerelatively free from magnetic influence.

The plate or trough ll may be provided with opposite side walls 26, andthe lower ends or the plate and walls extend downwardly beneath themiddlings basin water level IS, in order to prevent the loss of magneticmaterial to the hopper H, at the same time allowing the non-magmittedunder considerable pressure equally to both ends of this conduit l9 inorder to produce a sheetlike jet having'greatest intensity or volume andvelocity along the central longitudinal region of the space l8 asindicated diagrammatically by the force vectors 2'! in PBS. 2 and 4, thedot-and-dash lines and arrows representing jet intensity at the siteside zones 25 also be directed downwardly in contact with the materialconveyed on the upwardly traveling belt stretch [0 along the finalseparating and washing space i8, and this action is produced by theelongated deflector 2! shown in Fig. 3. The valve 23 is provided for thepurpose of controlling the magnitude or intensity .of the Jet, and maybedisposed within the common liquid supply piping system 22whichsubsequently branches out and connects with thejopposite ends ofthe slotted conduit I9 as illustrated in Figs. 2 and 4.

During normal operation of the improved magnetic separator, the belt 6is being advanced by the pulleys 1 8 so as to cause the loosely saggingplied to the lower surface of the loosely sagging 1 belt stretch l0 bythe feed tray H while the hoppers l2, M are filled with liquid to thelevels l3, l5 respectively. Liquid under pressure should be admittedthrough the pipes 22 to the opposite ends of the conduit l9 and theliquid thus admitted will cause a sheet-like spray jet to be deliveredfrom the slot 20 of the conduit is and this jet will be directed downalong the space IS in contact with the surface of the material on thebelt stretch ill, by the deflector 2 l. The material entering themachine will be promptly separated by the magnetic force into gangue ortailings and more or less magnetic material, and the tailings willsettle into the hopper l2 while the magnetic material includingconcentrates and middlings will adhere to the under surface of the beltstretch l0 and will be carried into the liquid basin within the hopperit. While passing through 'the basins inthe hoppers l2, M, the layer ofing action afforded by the liquid within these hoppers,- and when thelayer of material reaches the lower end of the trough I! it will be inrelatively clean condition. As the adhering and advancing layer ofmaterial is carried upwardly into the final separating space l8, it issubjected to the sweeping action of the flat sheet spray flowing atrelatively high velocity down through the final separating space I8, andthe sheet spray will promptly and eifectively remove the retainedmiddlings and gangue from the layer of concen-.

trates, and will rapidly wash and, because of its greater central poweror intensity, drive the renetic material .to be deposited withinthe'hopper Q moved middlings and gangue into the non-magnetic side zones25 located on opposite sides of the strong magnetic field, which arerelatively free from magnetic influence. The removed material and liquidwill then flow quickly down the non-magnetic zones 25 into the middlingshopper [4 where the solids will settle for subsequent treatment. In thismanner the concentrates are quickly and effectively purified and remainso and they will subsequently be released from the magnetic field at theupper end of the magnets 9 and will then be free to fall onto thedeflector device I6 into a hopper.

When the liquidunder pressure is admitted through the pipes 22 to theopposite ends of the conduit 19, the entering columns of liquid collidenear the center of the slot 20 and thus produce.

a sheet jet zhaving greatest intensity or volume and maximum velocity atthe mid-portion of the slot 20 as illustratedby the vectors in thedrawing, and this jet being directed downwardly along aeaaera in contactwith but not directly against the layer of material carried by thebelt'stretch it, will roll or sweep the middlings from the centralportions of the layer and will carry these middlings toward the sidenon-magnetic zones 25 from which they are quickly discharged intothehopper It without being recaptured by the magnetic field. In order toproduce a proper fiat sheet jet 2? which is capable of thus quicklyremoving the objectionable particles from the layer, the pressure of theentering liquid at the opposite ends of the conduit 69 should be asnearly equal as possible, and the deflector 2! should be so formed anddisposed that it will direct the flat sheet spray at a slight angleagainst the upwardly advancing bed of granular material. The flat jetwill not gouge into the layer of material with sumcient force to disturbthe stratiilcation.

of the material on the belt wherein the smaller particles, generallyconcentrates, are close to the under surface of the belt stretch it, andthe coarsest particles, generally middllngs, are on the lower surface oithe sheet of material on the belt and are thus exposed to the washingand removing action of the sheet jet. Fig. 5 is an enlarged view of aportion of the belt stretch it at the region of the sheet-like spray,and indicating the approximate relationship which most of the middlingsparticles will generally assume in respect to the concentrate particleson the belt. That is, the small black dots represent the concentrateparticles which are generally finest and closest to the belt, and thesomewhat larger circles shown with partially blackened areas, areintended to represent the relatively larger middlings particles, i. e.,particles containing both magnetic and non-magnetic material. Sincethese middlings particles are generally somewhat larger and do notcontain as high a percentage of magnetic material, they are notgenerally attracted so strongly to the belt as the finer magneticparticles and are thus carried along in a position well adapted to beswept off by the sheet-like spray when applied in the direction of thearrow, as indicated in Fig. 5. The intensity of the jet may be readilyvaried by manipulating the control valve 23.

From the foregoing detailed description it will be apparent that mypresent invention provides an improved magnetic separator which isextremely simple and compact in construction, highly efiicient inoperation, and which is less expensive to build and to operate than theprior separators of this general type. The improved machine alsoproduces a cleaner concentrate since the gangue and middlings are moreeffectively removed, and the flat sheet jet will also remove slimes andother foreign matter and actually consumes less water than was requiredwith the multiple forceful spray jets previously used. By virtue of thefact that the direction of the flat sheet jet is in opposition to thedirection of travel of the belt and is substantially parallel to thisbelt, the layer of ore deposited upon the belt stretch 50 will berestrained downwardly and held within the final washing zone for alonger period of time, thus also insuring more eficient final washing ofthe concentrates. The present improvement has proven highly satisfactoryand efficient in actual commercial use, and has made it possible toeliminate objectionable features of prior magnetic separators of thebelt and spray jet type, with simpler and more efiicient automaticallyfunctioning equipment.

It should be understood that it is not desired liquid basin, a conveyorhaving a surface movable upwardly at an oblique angle away from .the

liquid in said basin, trough-like means extending along said conveyorsurface to provide an inclined washing space extending upwardly awayfrom said basin, magnetic means for creating a strong magnetic fieldextending along and through said space, said trough-lik means proiectinglaterally beyond said field to provide side zones relatively free frommagnetic influence. and means for directing a sheet-like Jet 01 liquiddownwardly through said space with greatest volume and velocity near themid-portion of the space whereby non-magnetic material is washed towardsaid side zones.

2. In a magnetic separator, means forming a liquid basin, a conveyorbelt having a lower flat surface movable upwardly at an oblique angleaway from the liquid in said basin, trough-like means extending alongand beneath sai-d belt surface to provide an inclined washing spaceextending upwardly away from said basin, magnetic means disposed abovesaid surface for creating a strong magnetic field extending along andthrough said space, said trough-like means proiecting laterally beyondthe opposite sides of said field to provide side zones relatively freefrom magnetic influence, and means for directing a sheet-like jet ofliquid downwardly through said space with greatest volume and velocitynear the mid-portion of the space whereby non-magnetic material iswashed toward said side zones.

3. In a magnetic separator, means forming a liquid basin, a conveyorhaving a surface movable upwardly at an oblique angle from within theliquid in said basin, a series of magnets for creating a magnetic fieldextending along said conveyor to cause magnetic material toadhere tosaid surface, a trough extending along and in spaced relation to saidsurface to provide an inclined washing space extending upwardly awayfrom said basin and to also provide side zones relatively free frommagnetic influence, and means for directing a flat and wide jet ofliquid downwardly through said space so that said jet has greatestvolume and Velocity near the midportlon of the space wherebynon-magnetic material is washed into said basin through said side zones.

4. In a magnetic separator, means forming a liquid basin, a conveyorbelt having a lower flat surface movable upwardly at an oblique angleirom within the liquid in said basin, a series of magnets above saidbelt for creating a magnetic field extending along the conveyor to causemagnetic material to adhere to said surface, a trough extending alongand beneath and in spaced relation to said surfac to provide an inclinedwashing space extending upwardly away from said basin and to alsoprovide opposite side zones relatively free from magnetic influence, andmeans for directing a fiat and wide jet of liquid downwardly throughsaid space so that said jet'has greatest volume and velocity near themid-portion of the space whereby non-magnetic material is washed intosaid basin through said side zones.

5. In a magnetic separator, a hopper forming a settling basin, a beltconveyor having a lower surface movable upwardly away from said basin.magnets for creating a magnetic field sufficiently strong to causemagnetic material to adhere to said belt surface. a trough extendingalong and beneath said surface to provide an inclined washfor supportingand moving said belt stretch totravel from a position in proximity tothe liquid along an upwardly inclined path to a concentrates dischargeposition, magnetic means extending along above said belt stretch forcausing magnetic particles to adhere to the underside of the belt,trough-like means extending along said inclined path in spaced relationto the belt at regions above the liquid level to form a washing spacewithin the field of said magnetic means, said trough-like means alsoextending to zones alongside the belt which are beyond any stronginfiuence of said field, and means for directing a sheet-like jet ofwashing liquid downwardly along the underside of the belt in said space,said jet having substantially greater velocity and volume at themid-portion of the belt than at regions nearer said side zones, wherebyparticles embodying non-magnetic material are washed from the belt tothe side zones and thence downwardly along the trough-like means.

7. In a magnetic separator, a belt stretch, hopper means for containinga body of liquid, means for supporting and moving said belt stretch totravel from a position in contact with the liquid along an upwardlyinclined path to a concentrates discharge position, magnetic meansextending along above said belt stretch for causing magnetic particlesto adhere to the undersid of the belt, trough-like means extending alongsaid inclined path in spaced relation to the belt atregions above theliquid level to form a washin space within the field of said magneticmeans, said trough-like means also extending to zones alongside the beltwhich are beyond any strong influence of said field, a conduit having aslot extending transversely of and opening into said space, and meansfor connecting sources of wash liquid under pressure to both ends ofsaid conduit, whereby a sheet-like Jet of wash liquid is projected fromsaid slot downwardly along the underside of the Ht in said space, thetwo sources of the wash liquid causing said Jet to have greater velocityand volume at its mid-portion than at regions nearer said side zones tothereby cause particles embodying non-magnetic material to be swept fromthe belt to zones where the field is insufficient to cause substantialamounts thereof to be recaptured on the belt.

8. In a magnetic separator, a hopper forming a settling basin, a beltconveyor having a lower surface movable upwardly away from said basin,magnets for creating a magnetic field sumciently strong to causemagnetic material to adhere to said belt. surface, a trough extendingalong and beneath said surface to provide an inclined washing spaceextending upwardly away from said basin and having opposite side zoneswhich are relatively free from magnetic influence, a conduit having anelongated slotopening into an upper portion of said space and formed todirect a flat jet of washing liquid downwardly along said space. andmeans for delivering liquid under pressure into the opposite ends ofsaid conduit to cause said jet to have greatest intensity near itsmidportion and remote from said zones.

9. In a magnetic separator, means forming a settling basin, a conveyorhaving a lower surface movable upwardly away from said basin. magnetsfor creating a magnetic field adjacent to said surface, a trough forminga washing space extending along said surface and having its midportionwithin said field and opposite side zones relatively free from magneticinfluence, a conduit formed to direct a fiat jet of washing liquiddownwardly along said space, and means for deliverins liquid underpressure into said conduit to cause said jet to have greatest intensitynear the midportion of said space and remote fromsaid zones.

10. In a magnetic separator, means forming a settling basin, a conveyorhaving a lower surface movable upwardly away from said basin, magnetsfor creating a magnetic field adjacent to said surface, a trough forminga washing space extending along said surface and having its mid-portionwithin said field, a conduit formed to direct a fiat jet of washingliquid downwardly along said space toward said basin, and means fordelivering liquid under pressure into the opposite ends of said conduitto cause said jet to have greatestv intensity near the mid-portion ofsaid space.

11. In a magnetic separator, abelt conveyor having an inclined upwardlymovable stretch, magnetic means arranged along the upper surface of saidstretch for causing magnetic particles to adhere to the under surfacethereof, troughlike means extending along beneath said stretch in spacedrelation thereto, and means for projecting a sheet-like spray of washingliquid in a direction downwardly along a plane generally parallel tosaid stretch, between said stretch and trough-like means, said sprayprojecting means being so constructed and arranged that the spray alongregions nearer an edge of the belt has less force than along regionsmore widely spaced from the edge of the belt, whereby particlesdislodged from the belt by the spray tend to be swept to the side of thebelt.

12. In a magnetic separator, a belt conveyor having an inclined upwardlymovable stretch, magnetic means arranged along the upper surface of saidstretch for causing magnetic particles to adhere to the under surfacethereof, means for applying a liquid mixture of particles to be sepa-'rated, to the under side of a lower of said stretch, trough-like meansextending up along beneath said stretch in spaced relation thereto, andmeans for projecting a sheet-like spray of washing liquid havinggreatest intensity near its mid-portion, in a direction downwardly alonga plane generally parallel to said stretch, between said stretch andtrough-like means, at a region above the liquid level.

13. In a magnetic separator, conveyor means having an upwardly curvedupwardly movable surface portion, magnetic means arranged along theupper side of said surface portion for causing magnetic particles toadhere to the underside thereof, trough-like means extending alongbeneath said surface portion in spaced relation thereto, and means forprojecting a sheet-like spray of washing liquid in a directiondownwardly along a plane generallytangent to said surface portion,between said surface portion and said R l s -like means, said sprayprojecting means bein so constructed and arranged that the spray alongregions nearer an edge of the surface portion has less force than alongregions morewidely spaced from such edge, whereby particles dislodgedfrom the surface by the spray tend to be swept toward such edge.

14. In a magnetic separator, conveyor means having an upwardly curvedupwardly movable surface portion, magnetic means arranged along theupper side of said surface portion for causing magnetic particles toadhere to the underside thereof, means for applying a liquid mixture ofparticles to be separated, to the underside of a lower portion of saidconveyor means, trough-like means extending up along beneath saidsurface portion in spaced relation thereto, and means for projecting asheet-like spray of washing liquid 3 the liquid level.

10 having greatest intensity near its mid-portion, in a directiondownwardly along a plane generally tangent to said surface portion,between said portion and trough-like means, at a region above ROBERT E.CROCKE'I'I.

REFERENCES CIT-ED The following references are of record in the 1 fileof this patent:

UNITED STATES PATENTS

